Sea Buckthorn Pretreatment, Drying, and Processing of High-Quality Products: Current Status and Trends

Sea buckthorn is a kind of berry rich in nutritional and industrial value. Due to its thin skin, juicy pulp, and short shelf life, it is usually preserved via freezing methods or directly processed into sea buckthorn puree after harvest. It can also be dried and processed into products such as dried sea buckthorn fruit, freeze-dried sea buckthorn powder, and sea buckthorn oil. This review, therefore, provides an overview of the existing state of drying and high-quality processing of sea buckthorn. The effects of different pretreatment and drying techniques on the drying characteristics and quality of sea buckthorn and the existing problems of superior-quality processing of sea buckthorn products are summarised. The development trend of sea buckthorn drying methods and the ways to achieve high-quality processing of sea buckthorn products are indicated. These ways are mainly related to the following: (1) The application of combined pretreatment and drying techniques to find a balance between economy, ecology, and efficiency; (2) Introducing new online measurement and control technology into drying equipment; (3) Optimising the existing process to form a complete sea buckthorn industrial chain and develop the sea buckthorn deep-processing industry.

Novel sequential and simultaneous infrared-accelerated drying technologies for the food industry: Principles, applications and challenges

Infrared drying (IRD) is considered an innovative drying solution for the food industry with advantages of energy-saving potentials, reduced drying time and production cost-effectiveness. However, IRD also suffers from drawbacks such as weak penetrative ability, and product overheating and burning. Therefore, over the years, significant progress has been made to overcome these shortcomings by developing infrared-accelerated drying (IRAD) technology based on the combination of IRD with other drying technologies. Although several reviews have been published on IRD, no review focusing on IRAD is yet available. The current review presents up-to-date knowledge and findings on the applications of IRAD technologies for enhancing the quality and safety of food. The fundamental principles and characteristics of IRAD, energy-saving potentials, simulation and optimization approaches for enhancing efficiency, and developments in various acceleration approaches by combining with other drying techniques for achieving better end-products are discussed, and challenges and future work for developing the novel accelerated drying technology are also presented. Due to the synergistic effects of sequential or simultaneous combined drying methods, the total drying time and energy required are drastically lowered with most IRAD technologies, and consequently there are significant improvements in the sensory, nutritional, and safety attributes of dried food products with better appearance and quality. The development of multi-wavelength IRAD systems based on infrared absorption bands, and the incorporation of novel sensing techniques for real-time monitoring during drying will further enhance process efficiency and food quality and safety.

Effects of four different drying methods on the carotenoid composition and antioxidant capacity of dried Gac peel

BACKGROUND

Gac fruit (Momordica cochinchinensis Spreng.) is a rich source of carotenoids for the manufacture of powder, oil and capsules for food, cosmetic and pharmaceutical uses. Currently, only the aril of the Gac fruit is processed and the peel, similar to the other components, is discarded, although it contains high level of carotenoids, which could be extracted for commercial use. In the present study, four different drying methods (hot-air, vacuum, heat pump and freeze drying), different temperatures and drying times were investigated for producing dried Gac peel suitable for carotenoid extraction.

RESULTS

The drying methods and drying temperatures significantly affected the drying time, carotenoid content and antioxidant capacity of the dried Gac peel. Among the investigated drying methods, hot-air drying at 80 ^o C and vacuum drying at 50 ^o C produced dried Gac peel that exhibited the highest retention of carotenoids and the strongest antioxidant capacity.

CONCLUSION

Hot-air drying at 80 ^o C and vacuum drying at 50 ^o C are recommended for the drying of Gac peel. © 2016 Society of Chemical Industry.

Drying characteristics and quality of shiitake mushroom undergoing microwave-vacuum drying and microwave-vacuum combined with infrared drying

Shiitake mushrooms were dehydrated by two different drying methods, i.e., microwave-vacuum drying (MVD) and microwave-vacuum combined with infrared drying (MVD + IR). MVD was operated at microwave powers of 56, 143, 209 and 267 W under absolute pressures of 18.66, 29.32, 39.99 and 50.65 kPa, whereas infrared radiation was added in MVD + IR at 100 and 200 W. The effects of microwave power, absolute pressure and infrared power on drying characteristics, qualities and specific energy consumption were investigated. It was found that drying rate increased with lower absolute pressure, higher microwave power and higher infrared power. In particular, the results also indicated that drying undergoing MVD + IR could provide better qualities in terms of color of dried shiitake mushroom, rehydration ratio and texture of rehydrated ones. Furthermore, the drying characteristics were described by fitting data to six different drying models. Based on their coefficient of determination, root mean square error, residual of sum square and chi-square, Modified Page model could accurately predict moisture ratio for all drying conditions. Within the range of this study, the suitable drying condition with respect to the product qualities and energy consumption was MVD + IR drying at 267 W of microwave power, 18.66 kPa of absolute pressure and 200 W of infrared power.